Behind casing well perforating and isolation system and related methods

ABSTRACT

Disclosed is a novel unconventional multi-stage completions system and method called a behind casing perforation and isolation system and methods. It replaces the traditional plug and perforating electric wireline operations, and employs dual action charges and isolation valve control mechanism behind casing with the isolation valves (flapper, ball or similar) inside casing which enable the completion of unconventional multi-stage wells in a more time and cost-efficient way.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO AN APPENDIX SUBMITTED ON A COMPACT DISC AND INCORPORATED BYREFERENCE OF THE MATERIAL ON THE COMPACT DISC

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STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINTINVENTOR

Reserved for a later date, if necessary.

BACKGROUND OF THE INVENTION Field of Invention

The disclosed subject matter is in the field of unconventionalmultistage well completions and perforating systems in conjunction withfracking operations.

Background of the Invention

Petroleum or crude oil and Natural Gas are keystone natural resources.Petroleum may be used to make gasoline which is an important resource ofthe transportation industry. Petroleum may also be used to make otheritems such as tires, refrigerators, life jackets, and anesthetics.Natural gas may be used for heating, cooking, electricity generation, oras fuel for vehicles. Beyond its utility as an energy resource, naturalgas may also be used as a chemical feedstock for plastics or organicchemicals. In view of the foregoing, anyone can appreciate the need fortechnologies and related new methods of producing petroleum and naturalgas.

One issue with producing crude oil and natural gas is that theseproducts are generally found deep underground in rock formations. Theunderground location of these resources makes both oil and gas difficultto find and extract. But, because oil and gas are incredibly valuable,an entire industry has been built around the exploration, extraction,and processing of oil and gas.

Oil or natural gas extraction from an underground rock formationrequires the drilling of a hole or wellbore into the formation. Manydifferent methods exist by which the oil or natural gas can be broughtto the surface via the wellbore. In one method, oil may be recoveredwith artificial lifting mechanisms such as beam pumps, electricalsubmersible pumps, or by injecting fluids such as water, steam, orcarbon dioxide into a reservoir to increase reservoir pressure andenable the oil or natural gas to flow to surface. Using this method, theamount of oil and gas recovered relative to the amount of oil and gas inthe reservoir or recovery rate is determined in part by the geology ofthe well formation. Particularly important to recovery rates are thepermeability and the porosity of the rock formation. For instance, Shalerock formations tends to be more impermeable, inhibiting fluid flowswhile more permeable Sandstone rock formation allows fluids to flow morefreely yielding higher recovery rates.

When attempting to recover oil or gas from a more impermeable rockformation (unconventional formation), it may be necessary to performextra steps to increase formation permeability and recovery rates bystimulating the well. There are few stimulation methods that are usefulsuch as explosives, acid injection and hydraulic fracking. The mostcommon, safe, and beneficial stimulation method in these troublesomerock formations is hydraulic fracking.

Hydraulic fracturing or fracking is a well stimulation technique thatinvolves injecting fracking fluids consisting of water, chemicals andproppants under high pressure into well formations to crack reservoirrock thus allowing for petroleum, or natural gas to flow substantiallyuninhibited. After the complete fracking is done, the injected fluidsare flowed back from the well back to surface but leaving the hydraulicproppants within formation rock cracks to enable oil and gas continuousflow. Recently, hydraulic fracking has become a widespread stimulationmethod because of increased recovery rates and new accessibility tounconventional reservoirs such as shale formations, tight sands andcoals beds brought about by advances in drilling technology. Hydraulicfracking in conjunction with new drilling techniques like directionaldrilling, multi-well pads, seismic monitoring, and the like, has changedthe economics and the landscape of shale gas production leading to afracking boom in the United States.

Before fracking, the United States' oil production had been steadilydeclining for decades and had become highly susceptible to changes insupply from foreign exporters. However, fracking and its relatedadvances in shale production technology and methods has led the UnitedStates to become a net oil exporter and energy independent. In theUnited States, Shale oil production increased eight-fold after frackingwas commonplace.

Unconventional reservoirs within Oil and Gas industry are tightformation rocks and in general cannot be produced unless they arefractured, and therefore the completions and processes for producingunconventional wells are unique and different than any other sector. Itstarts with drilling wells that penetrate the target formation covering5,000 to 10,000 ft of horizontal reservoir section. Casing is run rightafter drilling the open hole section followed by cement operation tosecure the casing and establish well integrity. Hydraulic fracturing isthe chosen stimulation for developing nearly all unconventionalreservoirs economically using fracturing fluid, propping material, andpressure to create or restore small fractures in a geological formationand thereby to stimulate hydrocarbon production from oil or gas wells.In this process, hydraulic fracturing fluid is pumped from surface intothe wellbore traveling downhole till it reaches some perforated holes ata predetermined depth. The fluid travels through these holes across thecasing and surrounding cement into the reservoir to break the rocks andcreates conductive flow paths between the target reservoir and thewellbore. The high volume and high-pressured fluids create or restorefractures in the rocks so that hydrocarbon can move from geologicformations to fractures then to wellbores. The unconventional wells arecompleted in stages, usually ranges from 20 to 60 stages per well acrossthe lateral section. Each stage consists of one isolation plug andmultiple clusters (5 to 20 clusters) that are usually distributed acrossthe stage with specific hole (shot) size, number of holes per foot, andwith specific orientation across the casing depending on the fracdesign.

Wireline (or Electric Line) is the most common method for perforating(creating holes) and isolating each stage (via plugs). This is achievedby pumping the perforating guns and plug downhole utilizing water pumpsto the desired depth and then setting the plug before initiating theperforating guns via Electric Wireline cable. This provides simple,quick depth control and gun selectivity along with reduced safety risksof personnel and equipment. Pump Down Perforating (PDP) or Plug and Perf(PNP) means Wireline conveyed perforating services where fluid flow isused to transfer a plug and perforation assembly into a horizontalunconventional completion including associated depth control loggingservices. The detonating objective of a perforating gun is to provideholes within casing and achieve effective flow communication of fracfluid between the cased wellbore and productive reservoir. To achievethis, the perforating gun “penetrates” a pattern of perforations throughthe casing and cement sheath and into the productive formation. The gunusually contains several shaped explosive charges and available indifferent ranges of sizes and configurations.

The unconventional fracking operation is carried out by fracking onestage at a time till all stages are completed. The overall steps ofmultistage fracking operation now days are as follow:

-   -   1. Wireline tool string consisting of one plug and multiple guns        (depending on the number of clusters within the stage) is pumped        downhole within casing using water pumps that push the tool        string to the desired depth.    -   2. Wireline will set the plug at required depth then move up        hole to shoot the first gun (cluster) at a certain depth. After        shooting first gun, the Wireline move up hole again to shoot the        second gun. This process is repeated till all the guns        (clusters) are shot within the stage at the pre-determined        depths. The wireline is pulled out of hole at the end of this        operation.    -   3. After Wireline is out of hole, the high-pressure pumps will        start pumping the frac fluid into the wellbore (casing) till it        reaches the holes that were perforated via wireline earlier then        flow into formation rocks to create fractures. High volume of        frac fluid is pumped at high pressure till the required        formation rock area is fully fracked by frac fluid depending on        the frac design. The pumps are then shut off and well is handed        back to Wireline.    -   4. The Wireline runs in hole right after frac is done to set the        plug then shoot the guns (clusters) of the next stage followed        by frac with the same process as the previous stage. This        operation is repeated till all stages within the well are        completed.    -   5. Coiled tubing operations comes after all stages are completed        to drill all plugs and put the completed (fracked) well on        production. (note: some plugs are dissolvable and do not need        drilling with coiled tubing).

Wireline Pump Down Perforating (PDP) always strive to avoid being on anycritical path during frac operation, this is due to the high costassociated with Frac fleet. PDP operation can fall within below twooperational scenarios:

-   -   1. Single well operation (stacked frac):        The Frac operation is conducted on a single well with Wireline        being on critical path. i.e. Frac pumps are on standby till the        Wireline run is completed. This operation represents 20% of        North America completed wells    -   2. Multiple wells operation (zipper frac):        The Frac operation is conducted on multiple well keeping        Wireline away from critical path. On most occasions Wireline get        caught up and reduce the efficiency of Frac pumps. Due to        efficiency gains with multiple wells operation most companies        are drilling pads with 3-5 wells to utilize the frac as much as        possible which represents 80% of current frac market place.

LISTING OF RELATED ART

The following is a listing of related art.

U.S. Pat. No. 9,085,969 to Clay, shown above, which discloses,“Bi-directional shaped charges for perforating a wellbore.”

US20110017453A1 to Mytopher discloses a, “Wellbore subassembly with aperforating gun.”

US20050178554A1 to Hromas discloses a, “Technique and Apparatus forMultiple Zone Perforating.”

U.S. Pat. No. 6,009,947 to Wilson discloses a, “Casing conveyedperforator.”

U.S. Pat. No. 4,154,303 to Fournier discloses a, “Valve assembly forcontrolling liquid flow in a wellbore.”

US20180051532A1 to Smith discloses a, “Frac Plug with Integrated FlapperValve.”

US20130008671A1 to Booth discloses a, “Wellbore plug and method.”

U.S. Pat. No. 10,502,026 to Saraya discloses, “Methods and systems forfracing.”

U.S. Ser. No. 10/563,476 to Smith discloses a, “Frac plug withintegrated flapper valve.”

US20050115708A1 to Jabusch discloses a, “Method and system fortransmitting signals through a metal tubular.”

U.S. Pat. No. 6,536,524 to Snider discloses a, “Method and system forperforming a casing conveyed perforating process and other operations inwells.”

WO2000065195A1 to Snider discloses a, “Casing conveyed perforatingprocess and apparatus.”

U.S. Pat. No. 5,660,232 to Reinhardt discloses a, “Liner valve withexternally mounted perforation charges.”

U.S. Pat. No. 8,127,832 to Bond discloses, “Well stimulation usingreaction agents outside the casing.”

U.S. Pat. No. 9,664,013 to Coffey discloses, “Wellbore subassemblies andmethods for creating a flowpath.”

U.S. Pat. No. 4,832,134 to Gill discloses a, “Shaped charge assemblywith retaining clip.”

U.S. Ser. No. 10/246,974 to Greenway discloses a, “Punch and cut systemfor tubing.”

CA2953571C to Tolman discloses, “Methods for multi-zone fracturestimulation of a well.”

CN101148982A to Huisheng discloses a, “Side direction detonationsymmetrical dual action perforator.”

U.S. Pat. No. 6,684,954 to George discloses a, “Bi-directional explosivetransfer subassembly and method for use of same.”

U.S. Pat. No. 5,603,379 to Henke discloses a, “Bi-directional explosivetransfer apparatus and method.”

SUMMARY OF THE INVENTION

The main objective of this invention is to eliminate the Wireline PumpDown Perforating (PDP) process and replace it with an innovativeelectric behind casing perforating and isolation system. It is mainlyapplicable to the unconventional well completion applications. However,this invention can be also utilized in many different completionapplications which involve perforating operations, for example it canreplace the Tubing Conveyed Perforating system (TCP) within normal wellcompletions.

The invention approach is to install the perforating guns/charges andthe isolation valves control mechanisms on the outside (behind) casing.The isolation valve itself is to be installed inside casing to enablethe stage isolation. The casing assembly is then lowered into the openhole drilled section as per normal methods. The cementing operation tobe done after casing is in place as per current existing procedures.This novel system will enable direct communication from surface with theperforating guns and isolation valves via one or combination of anelectrical cable behind casing, series of acoustic repeaters/receiversbehind casing, electromagnetic repeaters/receivers behind casing orfluid pressure pulses within casing.

Below are the three major system components (surface, communication anddownhole) of the behind casing perforating and isolation system alongwith all its sub-components from top of well head all the way to thelateral casing downhole:

Surface System:

This is the surface electronic system which will communicate with alldownhole electronic components including addressable switches,perforating guns, detonators, and isolation valve control assemblies.The system has the telemetry software which enable shooting guns/stagesselectively by communicating with a specific downhole electricaddressable switch to initiate the perforating detonator. As well thesystem communicates with the isolation valve control assembly toinitiate the closure of the downhole isolation valve inside the casing.

Communication System:

The communication system is the means of sending the command fromsurface to shoot a detonator downhole, activate an isolation valvedownhole or get confirmation of downhole event back to surface. It canalso be the means of communication between different downhole stageassemblies. The communication is achieved by using one or combination ofbelow four options:

1. Electric Cable: The electric cable enables continuous communicationbetween surface system and downhole components. It is run behind casingutilizing cable clamps to secure around the casing. The cable istypically connected to the ballistic electric interface assembly. Anexample of this cable can be the one that is currently used with thesubmersible pump systems.

2. Acoustic Repeaters: An acoustic communication system which enablesending and receiving acoustic signals through casing. This can beachieved via acoustic repeaters or similar telemetry component installedbehind casing.

3. Electromagnetic waves: An electromagnetic waves communication systemwhich enable sending and receiving electromagnetic signals throughcasing and rock formation. This can be achieved via electromagneticrepeaters/receivers or similar telemetry component installed behindcasing.

4. Fluid Pressure Pulse: A fluid pressure pulse system that utilizespressure pulses created at surface by a telemetry pump or variablepressure source. These pulses travel within the fluid system insidecasing in which the commands are usually converted into an amplitude- orfrequency-modulated pattern of fluid pulses that is received downhole bya specific downhole pressure receiver.

Downhole System:

The downhole system consists of multiple stages which can reach up to 60stages depending on the well completion design. Each stage assemblyconsists of several gun assemblies and one ballistic isolation valveassembly connected to each other in series via downhole communicationcomponents explained in this document.

Below is full explanation of downhole stage assembly threesub-components:

1. Gun Assembly: Each stage has multiple gun assemblies depending on thestage design. The gun assembly itself consists of the followingcomponents:

a. Gun Housing: This is the housing that is attached to casing andsurrounding it at the same time. It can be installed in a spiral wayoutside of casing body and contains all gun assembly components insideto protect it from damage during running casing in hole and cementoperation later. The gun housing can be made of metal, composite, or anyother material.

b. Addressable Switch: This is an electronic device that has a specificelectronic unique address which is read by the surface acquisitionsystem. The addressable switch can be combined with the explosivedetonator in one assembly as well. The AS allows shooting all gunswithin same stage which are connected via ballistic electric line. Iteliminates the need to have it installed in each gun assembly within thestage but needs to be installed within the first gun assembly of eachfull stage to allow shooting the whole stage guns with one addressableswitch.

c. Explosive Detonator: This is the detonator that comes after theaddressable switch and connects to the explosive detonating cord whichgoes through the explosive perforating charges. The explosive detonatorand addressable switch can be combined in one assembly.

d. Explosive Detonating Cord: This is the cord that contains theexplosives inside to transfer the ballistic force from the detonator toexplosive charges.

e. Explosive Dual Action Perforating Charges: These charges can bedistributed with any specific shot density and phasing. The charges willeither face borehole to make a hole in casing or formation to penetratethe reservoir rock. The objective of these charges is to establishconnectivity between borehole and formation which enable Frac fluid toreach the formation during frac operation. There two options forconfiguring these charges; either two separate charges opposite indirection with one separate detonating cord for each charge (total twodetonating cords) or one combined charge with two opposite jetdirections (one detonating cord).

2. Downhole Communication Components: The main purpose of thesecomponents is to accomplish communication between the gun assemblies andballistic valve isolation assembly within each stage. It consists of thebelow optional items depending on the desired to communication method:

a. Ballistic Electric Line: The function of this line is to establishelectric and ballistic communication within each stage which consists ofseveral gun assemblies and one ballistic isolation valve assembly. Itconsists of a steel pipe that has a detonating cord inside with anelectric line which can be coax (surrounding the detonating cord) orsolid (adjacent to detonating cord).

b. Ballistic Electric Interface: This interface instrument objective isto enable the transition from electric cable to the ballistic electriccontrol line or the other way around.

3. Isolation Valve Assembly: This assembly has only the isolation valveitself inside casing while all other control and initiation mechanismsare placed behind casing. It consists of following components:

a. Isolation Valve Housing: This is the housing that is attached tocasing and surrounding it at the same time. It is installed outside ofthe casing body and contains isolation explosive detonator and isolationrelease assembly components inside to protect it from damage duringrunning casing in hole and cement operation later. The isolation valvehousing can be made of metal, composite, or any other material.

b. Addressable Switch: This is an electronic device that has a specificelectronic unique address which is read by the surface acquisitionsystem. The addressable switch can be combined with the explosivedetonator in one assembly as well. The addressable switch also allowsactivating the isolation valve inside casing after triggering thedetonator which is connected to the isolation release assembly. Everyballistic isolation valve assembly has one addressable switch connectedto it to allow triggering that specific isolation valve assembly.

c. Isolation Explosive Detonator: This detonator is connected todownhole communication system as well as the isolation release assembly.

d. Isolation Release Assembly: This is the assembly which activates theisolation valve to shut inside the casing. It has a release rod oranother suitable mechanism that prevents the isolation valve fromclosing unless the isolation explosive detonator was shot.

e. Isolation Valve: This is the isolation valve itself which existinside the casing and can be only shut in if the isolation releaseassembly was triggered by the Isolation explosive detonator or similarfunctional device. This can be a flapper valve, ball valve or any othersuitable isolation valve.

Step by Step and Operational Procedure:

The electric behind casing perforating and isolation system can work asper the following generic steps:

1. The supervisor sends a signal from surface to the addressable switchof the deepest isolation valve to trigger shooting the detonator thatinitiates the isolation release assembly to close the isolation valveinside casing. The confirmation of valve closure can be checked bypumping in fluid right after or via a confirmation signal from adownhole sensor.

2. The supervisor then sends a command to the correct addressable switchto trigger the detonation of the 1^(st) stage which is the deepest indepth and right above the isolation valve that was closed in previousstep. The stage contains multiple gun assemblies depending on wellcompletion design. Gun assemblies within same stage assembly can be allfired at once if utilizing electric cable communication. This isaccomplished via the ballistic electric line which contains thedetonating cord to transfer the ballistic energy. Another option wouldbe to shoot each gun assembly separately if utilizing the acousticrepeaters, electromagnetic waves, or pressure pulse communicationsystems. In case the electric cable communication is used then theaddressable switch can be mounted inside top gun of the stage (in casethe configuration is top bottom shooting) or the deepest gun of thestage (in case the configuration is bottom up shooting).

3. Frac operation is then done across the perforated guns within thespecific stage by pumping frac fluid at high pressure and volume as perthe completion design.

4. Once Frac operation is completed, supervisor repeats previous threesteps for the next stage moving up hole. This operation is repeated tillall stages within the well are completed.

5. Coiled tubing or any other suitable intervention comes after allstages are completed to drill or reopen all isolation valves and put thecompleted (fracked) well on production. (note: some isolation valves aredissolvable and do not need drilling with coiled tubing).

Benefits of the Invention:

The behind casing well perforating and isolation system may bepreferable to traditional perforation systems because the behind casingperforating and isolation system eliminates or substantially reduces theneed for wireline operation, pumps, and water. The elimination of thesecomponents may create environmental, efficiency, and cost benefits. Theelimination or reduction of the pumps has major potential environmentalbenefits. Pump elimination or reduction is estimated to save, on ayearly basis, billions of barrels of water, millions of gallons ofdiesel fuel, and decrease greenhouse gas emission (CO², NOX, CO,unburned Hydrocarbons) by about 20 million metric tons. There may alsobe an anticipated 20% yearly cost reduction and an expected 30% gain inpumping hour efficiency due to elimination or reduction of pump downperforating methods, pumps, and water. The behind casing wellperforating and isolation system may facilitate a 30% fracking fleetreduction yielding a significant reduction in total asset costs.

The behind casing well perforating and isolation system may alsoincrease efficiency by eliminating standby time, well switching time,time lost during wireline operations, time spent opening and closingwell heads, and time spent pressure testing between stages. The behindcasing well perforating and isolation system is expected to increasefracking efficiency by roughly 40% to 60%, yielding more than 20 pumpinghours daily. Further, the behind casing well perforating and isolationsystem may enable operators to frack each well completely before movingto the next well within same pad.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Other objectives of the disclosure will become apparent to those skilledin the art once the invention has been shown and described. The mannerin which these objectives and other desirable characteristics can beobtained is explained in the following description and attached figuresin which:

FIG. 1 is a schematic of an example of the behind casing wellperforating and isolation system and method consisting of multiplestages consisting of four-gun assembly per stage and six shots per gunutilizing electric cable communication and flapper isolation valve;

FIG. 2 is a schematic of an example of the behind casing wellperforating and isolation system and method consisting of one stage witheight-gun assembly per stage and three dual action shots per gunutilizing electric cable communication and flapper isolation valve;

FIG. 3 is a schematic of an example of the behind casing wellperforating and isolation system and method consisting of one stage withsix-gun assembly per stage and three dual action shots per gun utilizingacoustic repeaters communication and flapper isolation valve;

FIG. 4 is a schematic of an example of the behind casing wellperforating and isolation system and method consisting of one stage withone-gun assembly per stage and three dual action charges per gunutilizing fluid pressure pulse communication and ball isolation valve;

FIG. 5 is a side view of a complete one-gun assembly consisting of fivedual action charges (shots) per gun;

FIG. 6 is a perspective view of an alternative embodiment of the gunassembly consisting of three dual action charges and utilizing acousticrepeaters communication method;

FIG. 7 is a cross sectional view of a ballistic release isolation valveassembly showing an example of a flapper isolation valve;

FIG. 8 is a cross sectional view of the ballistic electric control linethat can be utilized in between gun assemblies employing any of thecommunication systems;

FIG. 9 is a cross sectional view of two possible charge configurationand penetration orientation, the left side charge configuration showstwo separate charges example and the right side charge configurationshows one combined charge example;

FIG. 10 is a flow chart that speaks to the steps involved in building awell and fracking a wellbore using the behind casing perforating andisolation system and methods;

FIG. 11 is a schematic of an example of the behind casing wellperforating and isolation system and method consisting of multiplestages with two-gun assembly having 4 shots per gun per stage andutilizing electric cable communication and flapper isolation valve;

FIG. 12 is a schematic of an example of the behind casing wellperforating and isolation system and method consisting of one stage withfour-gun assembly per stage and three dual action charges per gunutilizing electric cable communication with clamps and flapper isolationvalve;

FIG. 12a is a cross sectional view of a ballistic electric control linethat can be used with the cable communication system;

FIG. 12b is a right-side view of a partial gun assembly utilizing cablecommunications and three dual action shots;

FIG. 13 is a schematic of an alternative embodiment of the behind casingwell perforating and isolation system utilizing acoustic repeaters;

FIG. 13a is a cross sectional view of an acoustic isolation valveassembly showing the behind casing control mechanism as well as theflapper isolation valve inside casing; and,

FIG. 13b is a right-side view of an alternative embodiment of the gunassembly utilizing the acoustic repeaters.

It is to be noted, however, that the appended figures illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments that will be appreciated by thosereasonably skilled in the relevant arts. Also, figures are notnecessarily made to scale but are representative.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Disclosed may be a behind casing well perforating and isolation systemand methods. The system and related devices may be generalized as afracking, perforating and isolation system that places explosive chargesand isolation valve control mechanism on the outside of the metal wellcasing while keeping the isolation valve itself inside casing. Itutilizes a form of communication to surface that allows shooting theseexplosive charges and controlling the isolation valve. The more specificdetails of this system, devices, and related methods are disclosed inconnection with the figures.

FIG. 1 shows a behind casing perforating and isolation system 1schematic that speaks to an example of unconventional reservoircompletion system which would consist of multiple stages that can rangefrom 20 to 60 stages or more. One stage assembly 6 would consist of atleast one or multiple combined gun assemblies 8 and one isolation valveassembly 15. As shown, the behind casing well perforating and isolationsystem 1 may be generalized as a fracking perforating and isolationsystem that places a plurality of explosive dual action charges 8 ainside gun assembly 8 positioned outside a metal well casing 11 withinthe cement 12 surrounding it. When detonated, the plurality of dualaction charges 8 a create perforation tunnels 10 through the casing 11and cement 12 into formation rock 13 so that fracking fluid can bepumped down a wellbore 14 during fracking operation. The perforatedtunnels 10 also enable the oil or gas to flow into the cased wellbore 14after fracking the whole well stages and removing all isolation valves9.

The behind casing well perforating and isolation system 1 is a departurein some ways from traditional fracking systems. Like traditionalsystems, the behind casing well perforating system 1 penetrates thecasing 11, cement liner 12, and a formation rock 13. However, the behindcasing well perforating system 1 differs from traditional systems inthat the behind casing well perforating system 1 (a) places a pluralityof dual action perforation gun assemblies 8 outside the casing 11instead of inside the casing 11, (b) features isolation valve releasemechanisms outside casing 11 combined with isolation valves 9 (flappervalve in this example) inside casing 11 instead of traditional plugswhich is run with wireline 9, and, (c) allows for direct continuouscommunication between the surface system 2 and perforating gunassemblies 8 via an electrical cable 3, series of acoustic repeaters 4,electromagnetic communication or pressure pulse sensor 19, or acombination of all.

As mentioned, frac operations uses multiple stage assemblies 6 toperforate a wellbore 14. Using multiple stage assemblies 6 allowswellbore 14 to be thoroughly perforated and completed at the lateralreservoir section. As shown an electric cable 3 is connected to aballistic interface box 5 which uses a ballistic electric control line 7to connect a plurality of stage assemblies 6. A typical stage operationstarts with sending an electric signal to activate the closure ofisolation valve 9 which is part of the isolation valve assembly 15.After confirming the isolation valve 9 closure (flapper valve in thisexample), an electric signal is sent to shoot all charges 8 a which arearranged inside multiple gun assemblies 8 within the stage assembly 6right above the closed isolation valve 9. Once all gun assemblies 8within the stage assembly 6 are shot then the fracking pumps can startthe fracking operation within the same stage. This typical stageoperation is repeated till all stages within the wellbore 14 lateralreservoir section are completed.

FIG. 2 shows a schematic of the behind casing well perforating andisolation system 1. This schematic shows an overall system demonstrationof one stage 6. As shown in the schematic, a preferred embodiment of thebehind casing well perforating and isolation system 1 features aplurality of components behind and around casing 11. The stage assembly6 is communicating with a surface acquisition system 2 via an electriccable 3. The stage assembly 6 consists of a plurality of gun assemblies8 in series followed by the isolation valve assembly 15. The gunassemblies 8 and valve assembly 15 are controlled and activated byaddressable switches 8 b and detonators 15 c. Further, the mechanicalcomponent of the valve assembly 15 may also be controlled by a releasemechanism 15 a such as a rod to activate the isolation valve 9 closureinside casing. The gun assemblies 8 may be attached to the casing 11 viaa plurality of gun clamps 16. As shown, the gun assemblies 8 may beoriented anywhere along the outer face of the casing 11, in this examplefour of gun assembly 8 are placed at top section of casing 11 andanother four gun assembly 8 are placed at bottom section of casing 11.As shown in this example, each gun assembly 8 has three or four dualaction charges 8 a inside its housing 8 c.

FIG. 3 shows a behind casing perforating and isolation system 1schematic that speaks to a multistage assembly 6 that utilizes theacoustic repeaters 4 communication system. Referring to this schematic,the surface acquisition system 2 takes an inventory of the perforatinggun assemblies 8 and isolation valve assembly 15 which include isolationvalves 9 (flapper valve in this example) before, during, and after thecasing 11 is run and cemented in place. When the wellbore 14 lateral isready for stage perforation, the behind casing perforating and isolationvalve system 1 supervisor would trigger the deepest isolation valve 9(flapper valve) to close. The isolation valve 9 closure may be confirmedby pumping fluid downhole or preferably by a signal sent back from adownhole sensor. Then the supervisor may send a command to detonate allgun assemblies 8 within the specified stage assembly 6 which is above(shallower than) the closed isolation valve 9 but below (deeper than) asubsequent open isolation valve 9. The stage assembly 6 would containmultiple gun assemblies 8 mounted around casing (top and bottom ofcasing 11 in this example). The dual action charges 8 a gets fired aftersending the signal to a specific repeater 4 which activate battery 15 bto trigger detonator 15 c to shoot the dual action charges 8 a viadetonating cord 7 c. Fracking operation may then be done across thespecific stage assembly 6. Once fracking operation is completed, one mayrepeat the process of closing next shallower isolation valve 9 andfiring perforation gun assemblies 8 followed by fracking. This processis repeated until all wellbore lateral stages are completed.

FIG. 4 speaks to a pressure pulse sensor communication system 19 withinthe behind casing perforating and isolation system 1. The pressure pulsesensor system 19 utilizes a plurality of pulses 19 c created at thesurface by a telemetry pump 19 a. These pulses travel within the fluidinside the casing 11. The commands are usually converted into anamplitude- or frequency-modulated pattern of pulses 19 c that arereceived downhole by a downhole pressure receiver/repeater 19 b to shoota gun assembly 8 or close an isolation valve 9 (ball valve in thisexample) which is connected to an acoustic isolation valve assembly 19d.

FIG. 5. is showing the critical elements of perforation gun assembly 8,which consists of a plurality of dual action charges 8 a with specificrock formation penetration and casing penetration capabilities, anaddressable switch 8 b, a gun housing 8 c, the detonator 15 c and thedetonating cord 7 c. The gun housing 8 c is attached to and may surroundthe casing 11 as shown in FIG. 5. The gun housing 8 c may spiral aroundthe casing 11. The gun housing 8 c may contain and protect all other gunassembly 8 components when casing and cementing the wellbore 14. The gunhousing 8 c can be made of metal, composite, or any other material. Theaddressable switch 8 b is an electronic device that has a uniqueelectronic address which may be read by the surface acquisition system2. The addressable switch 8 b allows the frac crew to shoot all gunassemblies 8 within same stage 6. The detonator 15 c may be connected tothe addressable switch 8 b and the detonating cord 7 c through thecharges 8 a. The detonating cord 7 c may contain explosives whichtransfer ballistic force from the detonator 15 c to the charges 8 c. Theballistic electric control line 7 would go through all gun assemblies 8within same stage assembly 6 to enable shooting all guns within samestage by one detonator 15 c which can exist inside most top gun assembly8 (if top down shooting sequence is used) or inside most bottom gunassembly 8 (if bottom up shooting sequence is used).

FIG. 6 is a perspective view of an alternative embodiment of the gunassembly 8. This embodiment of the gun assembly 8 features an acousticrepeater 4. The acoustic repeater 4 may be connected via electric cableto the battery 15 b which may be connected to the detonator 15 c and agroup of dual action charges 8 a via detonating cord 7 c. Thisembodiment of the gun assembly 8 uses the acoustic repeater 4 to receivea signal through the casing 11 from another acoustic repeater withinprevious gun assembly 8. The acoustic repeaters 4 transfer the signal tothe subsequent gun assemblies' acoustic repeaters 4 till it reaches thecorrect depth/address gun assembly 8 commanding that specific gunassembly 8 to shoot its dual action charges 8 a. This process ofsignaling and charge activation may continue until an entire wellbore 14has been perforated.

Since there are no plugs, the behind casing perforating and isolationsystem 1 employs an isolation valve assembly 15. As shown by FIG. 7, thevalve assembly 15 is for example comprised of a detonator 15 c connectedto a release mechanism 15 a such as a rod, a ballistic electric controlline 7, a ballistic electric interface box 5, a valve housing 15 d, anaddressable switch 8 b, and in the preferred embodiment an isolationvalve 9 which is flapper in this example, however in other embodiments,the valve may be any isolation valve such as a ball valve. The isolationvalve assembly 15 as shown places the flapper valves 9 inside the casing11 and all other components outside the casing 11. The valve housing 15d surrounds and is attached to the casing 11. The valve housing 15 d isinstalled outside of the casing 11 and contains the detonator 15 c andrelease mechanism 15 a to protect them from damage during casing runningin open hole and cementing operation. The valve housing 15 d can be madeof metal, composite, or any other material.

The addressable switch 8 b has a unique electronic address which is readby the surface acquisition system 2. The addressable switch 8 b allowsthe isolation valve 9 (flapper, ball or similar) to be activated insidecasing after triggering the detonator 15 c which is connected to therelease mechanism 15 a. Every valve assembly 15 has one addressableswitch 8 b to allow specific activation of the valve assembly 15.Activating the detonator 15 c may release the rod 15 a which closes theisolation valve 9 (flapper, ball or similar) inside the casing 11. Thisisolation valve 9 closure is followed by shooting gun assemblies 8within that specific stage assembly 6 which enables fracking operationto start right after.

FIG. 8 shows a cross section of the ballistic electric control line 7.Another downhole communication component of the behind casingperforating and isolation system 1 is the ballistic electric controlline 7 which, as shown by FIG. 8 may be comprised of a steel pipe 7 athat has a detonating cord 7 c inside with an electric line 7 b whichcan be coaxial (surrounding the detonating cord 7 c) or solid (adjacentto detonating cord 7 c). The function of the ballistic electric controlline 7 is to establish electric and ballistic communication across anycombination of addressable switch 8 b, detonator 15 c, and dual charges8 a within gun assemblies 8 as well as through the valve assemblies 15.

FIG. 9 shows a cross section of a perforated wellbore. As shown in FIG.9 the dual action charges 8 a may be bidirectional, and may act inopposite directions, for instance, towards the wellbore 14 and towardsthe formation 13 simultaneously. The purpose of the charges 8 a which islocated inside gun assembly 8 is to establish fluid connectivity betweena wellbore 14 and the formation rock 13 across casing 11 and cement 12.The dual charges 8 a capabilities and configurations enable frackingfluid to reach the formation rock 13 during fracking operation. The dualaction charges 8 a can be made of either two separate charges (left sideof FIG. 9) or a single bi-directional or combined charge (right side ofFIG. 9).

FIG. 10 is a flow chart that speaks to the steps involved in building awell and fracking a wellbore 14 using the behind casing perforating andisolation system 1. This process may start with drilling a vertical thenhorizontal wellbore 14 into a rock formation 13, then inserting a casing11 into the wellbore 14. Once the casing 11 is in place, it is cased byfilling the wellbore 14 annulus with cement 12. Thereafter when the wellbecome ready for fracking operation, a signal will be sent to closedeepest isolation valve 9. A confirmation of valve closure is made byapplying pressure from surface and holding pressure or a signal back tosurface. The next step would be shooting a plurality of dual actioncharges 8 a inside perforating gun assemblies 8 within first stageassembly 6. Once the first stage assembly 6 has been perforated afracking fluid may be pumped into the wellbore 14 at high pressure intothe formation rock 13, this concludes a complete stage frackingoperation. The subprocess of closing valves 9 then firing gun assemblies8 after that pumping fracking fluid may be repeated indefinitely untilthe full lateral wellbore 14 has been adequately fracked. After thefracking pumps are removed from surface, a suitable interventionmechanism is used to drill out or reopen all isolation valves 9. Thiswill enable the well to be put on production as soon as propercompletion components are run in hole if needed.

FIG. 11 is a schematic showing the main components of a behind casingperforating and isolation system 1 utilizing cable communication whereeach stage assembly 6 consist of two-gun assemblies with four dualcharges 8 a per gun assembly 8. The surface acquisition system 2 isconnected to stage assembly 6 via cable 3 which runs behind casing fromsurface to electric interface box 5 which serves as an interface toenable the information transmission from the electric cable 3 to aballistic electric control line 7 which runs across all stage assemblies6 which includes gun assemblies 8 and isolation valve assemblies 15.

FIG. 12 shows another schematic of the behind casing perforating andisolation system 1. As shown in the schematic, a preferred embodiment ofthe behind casing well perforating system 1 features a plurality ofcomponents. The behind casing well perforating system 1 features thesurface acquisition system 2 which facilitates surface communicationwith downhole components via an electric cable placed behind the casing11. The surface acquisition system 2 may enable shooting gun assembles 2and closing isolation valve 9 (flapper or similar) by activatingisolation valve assembly 15. A communication system may be created bycomplex coordination between an electric cable 3, a plurality ofacoustic repeaters 3, and electromagnetic waves or pressure sensorsystem 19. The electric cable 3 establishes continuous communicationwith the downhole gun assemblies 8 and ballistic isolation valvesassemblies 15. The electric cable 3 may also be placed behind the casing11 utilizing a plurality of cable clamps 16. The system will enable asurface operator to shoot a gun assembly 8 downhole, activate anisolation valve 9 downhole, or get confirmation of downhole event.Another important component is a ballistic and electric interface box 5which serves as an interface to enable the information transmission fromthe electric cable 3 to the ballistic electric control line 7.

A critical element of perforation operations is a gun assembly 8explained in FIG. 12b which consists of an addressable switch 8 b anddetonator 15 c installed at the top of the gun assembly 8 followed byother gun assemblies 8 and at least one isolation valve assembly 15(flapper or similar) in series. Another downhole communication componentof the system 1 is the ballistic electric control line 7 which, as shownby FIG. 2a consists of a steel pipe 7 a that has a detonating cord 7 cinside with an electric line 7 b which can be coaxial (surrounding thedetonating cord 7 c) or solid (adjacent to detonating cord 7 c). Thefunction of the ballistic electric control line 7 is to establishelectric and ballistic communication with an addressable switch 8 b,detonator 15 c, and charges 8 a across all gun assemblies 8 andisolation valves assemblies 15.

FIG. 13 speaks to a single stage example of the behind casingperforating and isolation system 1 consisting of total three gunassemblies 6 with three dual charges 8 a per gun assembly 8 incombination of one acoustic isolation valve assembly 15 which includesisolation valve 9. The shown embodiment of the behind casing perforatingsystem 1 features a communication system comprised of acoustic repeaters4. The surface acquisition system communicates with the gun assemblies 8and isolation valve assembly 15 via acoustic repeaters 4. FIG. 13bspeaks to the gun assembly. This embodiment features an acousticrepeater 4. The acoustic repeater 4 may be connected via detonating cord7 c to the battery 15 b which may be connected to the detonator 15 c anda group of charges 8 a. This embodiment of the gun assembly 8 uses theacoustic repeater 4 to receive/send a signal through the casing 11from/to another acoustic repeater which is installed at a distancebefore/after its position. FIG. 13a speaks to the details of theacoustic isolation valve assembly 15. The valve assembly 15 is comprisedof an acoustic repeater 4 connected to battery 15 b connected to adetonator 15 c connected to a release mechanism 15 a such as a rod, avalve housing 15 d, and in the preferred embodiment an isolation valve 9(flapper, ball or similar). The isolation valve assembly 15 purpose isto isolate the zone below stage assembly 6 by closing the isolationvalve 9 before perforation process to commence.

Although the method and apparatus is described above in terms of variousexemplary embodiments and implementations, it should be understood thatthe various features, aspects and functionality described in one or moreof the individual embodiments are not limited in their applicability tothe particular embodiment with which they are described, but insteadmight be applied, alone or in various combinations, to one or more ofthe other embodiments of the disclosed method and apparatus, whether ornot such embodiments are described and whether or not such features arepresented as being a part of a described embodiment. Thus, the breadthand scope of the claimed invention should not be limited by any of theabove-described embodiments.

Terms and phrases used in this document, and variations thereof, unlessotherwise expressly stated, should be construed as open-ended as opposedto limiting. As examples of the foregoing: the term “including” shouldbe read as meaning “including, without limitation” or the like, the term“example” is used to provide exemplary instances of the item indiscussion, not an exhaustive or limiting list thereof, the terms “a” or“an” should be read as meaning “at least one,” “one or more,” or thelike, and adjectives such as “conventional,” “traditional,” “normal,”“standard,” “known” and terms of similar meaning should not be construedas limiting the item described to a given time period or to an itemavailable as of a given time, but instead should be read to encompassconventional, traditional, normal, or standard technologies that mightbe available or known now or at any time in the future. Likewise, wherethis document refers to technologies that would be apparent or known toone of ordinary skill in the art, such technologies encompass thoseapparent or known to the skilled artisan now or at any time in thefuture.

The presence of broadening words and phrases such as “one or more,” “atleast,” “but not limited to” or other like phrases in some instancesshall not be read to mean that the narrower case is intended or requiredin instances where such broadening phrases might be absent. The use ofthe term “assembly” does not imply that the components or functionalitydescribed or claimed as part of the module are all configured in acommon package. Indeed, any or all the various components of a module,whether control logic or other components, might be combined in a singlepackage or separately maintained and might further be distributed acrossmultiple locations.

Additionally, the various embodiments set forth herein are described interms of exemplary block diagrams, flow charts and other illustrations.As will become apparent to one of ordinary skill in the art afterreading this document, the illustrated embodiments and their variousalternatives might be implemented without confinement to the illustratedexamples. For example, block diagrams and their accompanying descriptionshould not be construed as mandating a particular architecture orconfiguration.

All original claims submitted with this specification are incorporatedby reference in their entirety as if fully set forth herein.

I claim:
 1. The behind casing perforating and isolation system includesone or more stage assemblies consisting of: at least one perforation gunassembly; and, at least one isolation valve assembly.
 2. The behindcasing perforating and isolation system of claim 1 wherein theperforation gun assembly features a plurality of dual action explosivecharges.
 3. The behind casing perforation and isolation system of claim2 wherein the perforation gun assembly is placed outside a wellborecasing.
 4. The behind casing perforation and isolation system of claim 3wherein the isolation valve assembly features isolation valve releasemechanism behind casing and isolation valve inside casing.
 5. The behindcasing perforation and isolation system of claim 4 further comprising acommunication system that includes one or combination of followingmethods: electric cable, acoustic repeater, electromagnetic waves, orfluid pressure pulse systems.
 6. The behind casing perforation andisolation system of claim 5 wherein the dual action charge is comprisedof two joint explosive charges or two single explosive charges
 7. Abehind casing perforation system comprising: at least one stageassembly.
 8. The behind casing perforation and isolation system of claim7 wherein the stage assembly is comprised of at least one addressableswitch, at least one detonator, a plurality of gun assemblies, and aplurality of isolation valves assemblies (flapper, ball or similarvalves) in series.
 9. The behind casing perforation and isolation systemof claim 8 further comprising a surface acquisition system.
 10. Thebehind casing perforation and isolation system of claim 9 furthercomprising an electric cable connected to gun assemblies and isolationvalve assemblies.
 11. The behind casing perforation and isolation systemof claim 10 further comprising a ballistic and electric interface box.12. The behind casing perforation and isolation system of claim 11further comprising a plurality of acoustic repeaters or electromagneticwaves repeaters
 13. The behind casing perforation and isolation systemof claim 12 further comprising a ballistic electric control line. 14.The behind casing perforation and isolation system of claim 13 whereinthe ballistic electric control line is comprised of a steel pipe, adetonating cord and an electric line.
 15. A method of building a wellcomprising: drilling a vertical then horizontal wellbore into a rockformation; casing the wellbore; filling a wellbore annulus with cement;closing isolation valve and, firing a plurality of dual actionperforating guns in a first stage.
 16. The method of claim 15 furthercomprising closing an isolation valve for every stage assembly.
 17. Themethod of claim 16 confirming valve closure with a sensor or building uppressure.
 18. The method of claim 17 further comprising firing multipleplurality of dual action charges and perforating guns.
 19. The method ofclaim 18 further comprising pumping a fracking fluid into the wellbore.20. The method of claim 19 further comprising drilling out or reopeningthe isolations valves with suitable well intervention technique ifneeded.
 21. The method of claim 20 further comprising flowing back afracking fluid out of the wellbore before putting well on production.